In the title compound, C(13)H(10)O(4), an analog of acetylsalicylic acid, the naphthalene unit is twisted slightly due to ortho disubstitution [dihedral angle between conjugated rings system in the naphthalene unit = 2.0 (2)degrees]. The mean planes of the carboxylic and ester groups are almost coplanar and perpendicular, respectively, to the mean plane of the conjugated aromatic system, making dihedral angles of 8.9 (3) and 89.3 (1)degrees. In the crystal, molecules are paired through their carboxylic groups by the typical centrosym-metric O-H center dot center dot center dot O interactions with R(2)(2)(8) hydrogen-bond motifs. In addition, several weak C-H center dot center dot center dot O intermolecular contacts are also observed. Finally, the molecules are stacked along crystallographic [100] and [010] directions.